P1609: CAPLACIZUMAB THERAPY IN OLDER PATIENTS (≥60 YEARS) WITH IMMUNE THROMBOTIC THROMBOCYTOPENIC PURPURA (ITTP). RESULTS OF THE SPANISH TTP REGISTRY
Authors: Javier DE LA Rubia, Inés Gómez-Seguí, Joan Cid, David Valcárcel, Rosa Goterris, Miguel Fernández Zarzoso, María Eva Mingot-Castellano, Cristina Pascual Izquierdo, Ana Oliva Hernández, Jorge Martínez Nieto, Laura F. Ávila Idrovo, María Liz Paciello Coronel, Luis M. Hernández
Journal: HemaSphere (2023)

Topic: 32. Platelet disorders Background: Immune thrombotic thrombocytopenic purpura (iTTP) is caused by severely reduced activity of ADAMTS13 due to the development of autoantibodies against ADAMTS13. The median age at diagnosis of iTTP is around the fourth decade of life and patients ≥60 years account for less than 25% of cases. Current treatment of iTTP consists of the association of daily plasma exchange (PEx), immunosuppressive therapy with glucocorticoids ± rituximab, and caplacizumab. However, there is scarce information about the safety and efficacy of caplacizumab in patients with iTTP over 60 years of age. Aims: In this study, we analyze the efficacy and safety of the administration of caplacizumab as part of the treatment of a first episode of iTTP in a series of 14 patients ≥60 years and compare the results with patients <60 years included in the Spanish TTP registry and receiving caplacizumab as well. Methods: We queried the Spanish TTP Registry for adult patients (>18 years) with iTTP diagnosed between 2016 and 2021. Inclusion criteria were a first episode of iTTP, ADAMTS13 levels <10%, treatment with PEx, immunosuppression with steroids, and caplacizumab ± rituximab. Safety and tolerability were the primary objectives. Outcome definitions were based on those published by the International Working Group (Scully et al. 2017). Results: Sixty patients who satisfied the inclusion criteria were included, 14 with ≥60 years (Group 1) and 46 with <60 years (Group 2). The median (range) age was 62 (60-74) in Group 1 and 43 (19-59) in Group 2. Eight (57%) and 33 (72%) were women in Groups 1 and 2, respectively. Two patients in Group 1 had a serum creatinine value ≥2 mg/dL at diagnosis vs. none in Group 2, while 5 and 11 patients had raised serum ANA levels in Groups 1 and 2, respectively. The remaining baseline characteristics were similar in both groups (Table). Rituximab was administered to 11 (78.5%) patients in Group 1 and 34 (74%) in Group 2. Finally, no patient received concomitant prophylactic antiaggregant or anticoagulant drugs. Caplacizumab was administered as part of the therapy of the first episode of iTTP in 45 patients (11 in Group 1 and 34 in Group 2), a median of 2 (interquartile range [IQR], 0-12) and 4 (IQR, 1.5-10.5) days after diagnosis in Groups 1 and 2, respectively. Fourteen patients (3 in Group 1 and 11 in Group 2) received caplacizumab after exacerbation of this episode, and one patient <60 years received caplacizumab due to refractory disease. The median (range) duration of hospitalization was 15 (5-72) and 18 (5-55) days in Groups 1 and 2, respectively. Eight (57%) and 31 (72%) patients underwent hospitalization in the ICU among patients ≥60 and <60 years, respectively, with a median stay of 3 days in both groups. From the safety point of view, only one patient ≥60 years showed moderate epistaxis. There were no severe treatment-emergent adverse events, and no patient discontinued therapy due to treatment-related toxicity. With a median follow-up of 12 months, two patients (one in each group) suffered an exacerbation, and no patient relapsed after treatment. Finally, one patient ≥60 years died on day 12 after diagnosis due to multiorgan failure that was not considered caplacizumab-related, but progression of iTTP. Summary/Conclusion: The findings from this cohort of iTTP patients reflect the improvement of prognosis, including patients ≥60 years with iTTP, and support the efficacy of caplacizumab as part of the front-line treatment of patients with iTTP regardless of age. Likewise, our preliminary results confirm the safety profile of this nanobody in elderly patients, with no new safety concerns reported.Keywords: Elderly, Therapy, Thrombotic thrombocytopenic purpura (TTP), aPTT